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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

346                                 ALASKAN GLACIER STUDIES
College Fiord at Point Pakenham, where these fiords unite to make Port Wells. The one at the mouth of Barry Arm has 354 feet of water in mid-fiord but rises 22 feet higher than the bottom a mile farther up the fiord. Its ends are marked by spits running out from each shore  and lj miles respectively, where alongshore currents could not possibly have built spits without a shallow foundation, such as a moraine to guide them. They are, moreover, composed of morainic material too large to have been carried and built in this specialized form by anything but ice. The one on the western shore is double, suggesting two halts of the expanded glacier.
The southernmost of the two submerged moraines at the entrance to College Fiord has 276 feet of water in mid-fiord, rising 90 feet above the fiord bottom half a mile to the north and 450 feet above that to the south. Its visible portion consists of a moraine bar extending a mile and three-eighths from Pt. Pakenham on the west; but there does not seem to be any similar bar extending out from the eastern shore. The material in the western bar includes coarse angular bowlders, and the part nearest shore supports clumps of large trees.
A mile and a quarter north of this is another submerged bar lying at a depth of less than 294 feet. It rises approximately 50 and 70 feet above the fiord bottom to the north and south and has a point visible at low tide, extending out toward it from either shore.
These three submerged bars, interpreted as moraines, seem to have been built just after the Port Wells Glacier had retreated far enough to separate the Barry Arm and College Fiord ice tongues; and the double character in each case suggests either two halts or a readvance.
A moraine similar to these is possibly being built at the present terminus of Harriman Glacier, for: (a) there are no rock ledges exposed, as at Surprise Glacier, to suggest that the head of the fiord has been reached; (b) a partial shoal fronted the terminus of the glacier in 1899; and (c) six or seven hundred feet from the ice cliff of 1910, after 700 to 1050 feet of advance, the water was only 90 feet deep, in striking contrast to the depth near the front of other large tidal glaciers in Prince William Sound. Glacial streams as well as ice borne detritus, are doubtless contributing to it.
RELATIONSHIPS OP VEGETATION TO GLACIAL HISTORY
The vegetation in Port Wells, Barry Arm, and Harriman Fiord furnishes much evidence of the recent history of the region. There is thick coniferous forest on the lower slopes of Port Wells and Barry Arm up to Pt. Doran. Above the barren zone of Barry Glacier it extends continuously up to Cascade and Coxe Glaciers; and, even beyond these cascading glaciers, vegetation extends for a short distance, the alder thickets extending farther than the spruce and hemlock. Barren zones around Serpentine, Surprise, and Toboggan Glaciers also interrupt the continuity of the coniferous forest, which extends southward to Baker Glacier on the western side of Harriman Fiord. There is one small clump of conifers between Baker and Detached Glaciers 600 or 700 feet above sea level, west of which alder thickets extend to Surprise Glacier on the northern shore of that inlet. Alders grow between Surprise and Cataract Glaciers on the southern side of Surprise Inlet, and alders and two stunted spruces are found between Cataract Glacier and Harriman Fiord. The eastern side of Harriman Fiord has thick spruce and hemlock